Regensburg 2000 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 7: Postersitzung I: Amorphe- und Tunnelsysteme (1-8), Mesoskopische Systeme (9-21), Schwere Fermionen (22-32), Kernmagnetismus (33-34), Josephson-Kontakte und SQUIDs (35-45), TT-Detektoren und Kryotechnik (46-49)
TT 7.29: Poster
Montag, 27. März 2000, 14:30–18:00, A
High-resolution magnetization studies of the heavy-fermion superconductor CeCu2Si2 at very low temperatures and high magnetic fields. — •T. Tayama1, T. Lühmann1, M. Lang1, F. Steglich1, and W. Aßmus2 — 1Max-Planck Institut für Chemische Pysik fester Stoffe, Nöthnitzer Str. 48, 01187 Dresden — 2Institut für Physik, SFB 252, Universität Frankfurt, 60325 Frankfurt
A Faraday force magnetometer has been developed for static magnetization
measurements at very low temperatures down to 50 mK and in magnetic fields up
to 14 T. It consists of a plate capacitor with one movable plate placed in a
magnetic field with well-defined field gradient. This device enabled us to
perform high-resolution (10−7 emu) measurements of the static
magnetization of the heavy-fermion superconductor CeCu2Si2 as a function
of both field and temperature.
One of the most interesting problems of this
compound is the complicated B-T phase diagram, which shows the superconducting
phase at about 0.7 K in addition to two phases A and B whose origin is still
under discussion. The temperature dependence of the magnetization is found to
show a small but appreciable cusp when entering phase A/B from the
paramagnetic
high-temperature phase, consistent with an antiferromagnetically ordered state
below TA/B. Besides the B-T phase diagram we also discuss the
behaviour of
the magnetization in the paramagnetic state, where in various CeCu2Si2
single crystals distinct non-fermi-liquid phenomena were observed both in
resistivity and specific-heat.